.nav-header{
  height: px2rem(54px);
  width: 100%;
  position: fixed;
  top: 0px;
  left: 0px;
  line-height: px2rem(54px);
  text-align: center;
  border-bottom: 1px solid #efecec;
  z-index: 99;
  background-color: #fff;
  font-size: px2rem(16px);
  color: #5f5c5c;
  .icon-back{
    width: px2rem(20px);
    height: px2rem(20px);
    position: absolute;
    left: px2rem(10px);
    top: px2rem(17px);
    background: url("./img/back.png") no-repeat;
    background-size: cover;
  }
}
